3T is nothing, I massed a 3T planet def down just to take and dump the planet cause it was funny. Honestly, it depends on the planet. 100000 def facilities on a mind blowing planet will give you 300 bill def and that keeps most noobs away, still easily massed, but if it's a good planet the only way to keep it safe is with Merlins and PPT's.

yea pretty much. practically any planet can be taken/massed these days mostly due to the fact that building a def high enough to stop it, costs so much that the planet could be twice as good as it is if you put the naq into that. and you could arguably remake another planet for just as much as it would cost you to defend it.